Technical Field
The present disclosure relates to the technical field of photovoltaic power generation, and in particular to a pre-charge circuit and a photovoltaic inverter.
Background of the Technology
A photovoltaic inverter, which is an energy conversion device in a photovoltaic power generation system, serves to convert a direct current output from a photovoltaic battery into an alternating current and then transfer the alternating current to an electrical grid.
In the conventional technology, in order to turn on the photovoltaic inverter by a high voltage of the photovoltaic battery, the photovoltaic inverter is electrically connected to a pre-charge circuit as shown in FIG. 1 to raise a pre-charge voltage of a direct current bus, thereby avoiding a current impact caused by a significant voltage difference between the voltage of the battery and the voltage of the direct current bus at an instant when the photovoltaic inverter is electrically connected to the photovoltaic battery. In addition, in a case that the photovoltaic inverter operates in a static var generator mode, the direct current bus still needs to be pre-charged, to avoid a current impact caused by a significant voltage difference between a voltage of the direct current bus and a peak voltage of the electrical grid at an instant when a grid-connection is performed.
In the above pre-charge solution, a full bridge rectification with a diode uncontrolled rectifier bridge is adopted. A rectified voltage will not exceed a peak voltage of the electrical grid. In addition, due to a voltage drop caused by the rectifier component and current-limiting component and a load on a direct current side of the photovoltaic inverter, the actual rectified voltage may be lower, resulting in that the pre-charge voltage of the direct current bus cannot reach the voltage of the electrical grid or the voltage of the photovoltaic battery, and therefore it is impossible to avoid the current impact generated when the photovoltaic inverter is electrically connected to the photovoltaic battery or when a grid-connection is performed.